Claim and Claim Adjustment Expense Reserves, Long Term Care Policyholder Reserves (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Life and Group Policyholder Reserves [Abstract]
Premium deficiency in long term future policy benefit reserves	$ 74	$ 216	$ 74	$ 216
Lower Discount Rate Assumptions and Mortality Assumption Changes [Member]
Life and Group Policyholder Reserves [Abstract]
Increase (decrease) in claim and claim adjustment expense reserves	46
Lower Claim Severity [Member]
Life and Group Policyholder Reserves [Abstract]
Increase (decrease) in claim and claim adjustment expense reserves	$ (37)	$ (56)